There is no question that Americans exceed the recommended levels of sodium intake by significant amounts. High intake levels are evident regardless of life stage, gender, race/ethnicity, and income. Further, estimated intake has trended upward when compared to the first National Health and Nutrition Examination Survey (NHANES) conducted in 1971–1974.

Very little sodium occurs naturally in foods, and the majority of sodium in the U.S. diet is from sodium added during food processing and by restaurants and other foodservice operations such as cafeterias and catering services. Salt is the greatest contributor of sodium to the diet, but data are inadequate to quantify with any certainty the proportions attributable to sodium chloride (i.e., salt) compared to other dietary sources of sodium such as sodium bicarbonate, sodium benzoate, and sodium ascorbate.

The 2005 Dietary Guidelines for Americans recommends that persons 2 or more years of age consume less than 2,300 mg of sodium per day (USDA/HHS, 2005). These recommendations further specify that many persons will benefit from further reductions in salt intake, including people with hypertension, African Americans, and middle- and older-aged adults (DGAC, 2005). The Centers for Disease Control and Prevention (CDC) recently reported that these special at-risk persons now constitute approximately 69 percent of the U.S. adult population (CDC, 2009).

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5 Sodium Intake Estimates for 2003–2006 and Description of Dietary Sources ."
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5
Sodium Intake Estimates for 2003–2006
and Description of Dietary Sources
T
here is no question that Americans exceed the recommended levels
of sodium intake by significant amounts. High intake levels are
evident regardless of life stage, gender, race/ethnicity, and income.
Further, estimated intake has trended upward when compared to the first
National Health and Nutrition Examination Survey (NHANES) conducted
in 1971–1974.
Very little sodium occurs naturally in foods, and the majority of so-
dium in the U.S. diet is from sodium added during food processing and
by restaurants and other foodservice operations such as cafeterias and
catering services. Salt is the greatest contributor of sodium to the diet,
but data are inadequate to quantify with any certainty the proportions
attributable to sodium chloride (i.e., salt) compared to other dietary
sources of sodium such as sodium bicarbonate, sodium benzoate, and
sodium ascorbate.
The 2005 Dietary Guidelines for Americans recommends that persons
2 or more years of age consume less than 2,300 mg of sodium per day
(USDA/HHS, 2005). These recommendations further specify that many
persons will benefit from further reductions in salt intake, including people
with hypertension, African Americans, and middle- and older-aged adults
(DGAC, 2005). The Centers for Disease Control and Prevention (CDC)
recently reported that these special at-risk persons now constitute approxi-
mately 69 percent of the U.S. adult population (CDC, 2009).
The Institute of Medicine (IOM) established reference values for so-

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0 STRATEGIES TO REDUCE SODIUM INTAKE
dium for the first time in 2005 (IOM, 2005). An Adequate Intake1 (AI) was
established by the IOM ranging from 1,000 to 1,500 mg for persons 2 or
more years of age depending on age, and is a value that reflects the recom-
mended average daily intake level based on observed or experimentally
determined approximations or estimates of nutrient intake.2 The IOM also
established a Tolerable Upper Level of Intake3 (UL) for sodium ranging
from 1,500 to 2,300 mg depending upon age, which is the highest daily
intake level that is likely to pose no risk of adverse health effects to almost
all individuals in the general population (IOM, 2005).
In setting the stage for the committee’s deliberations, Chapter 2 pro-
vides an overview of existing information about sodium intake in relation
to evaluating the effectiveness of the major national public health initiatives.
This chapter presents the results of analyses4 conducted for the committee’s
study using data from NHANES,5 a large nationally representative survey
conducted by CDC. Specifically, data from the 2003–2006 NHANES period
were analyzed in order to specify current sodium intake. These dietary in-
take data are collected in the component of the NHANES known as What
We Eat in America, but for the purposes of simplicity this chapter refers
to them as NHANES data. The 2003–2006 NHANES data were also used
to characterize current contributions to the diet based on food categories
and to examine contributions to intake made by foods “from home” versus
those “away from home.” Issues of monitoring and surveillance of intake
and related factors are also considered.
Background information on the NHANES and the methodologies used
1 Adequate Intake: IOM reference value: the recommended average daily intake level based
on observed or experimentally determined approximations of estimates of nutrient intake
by a group (or groups) of apparently healthy people that are assumed to be adequate (IOM,
2006).
2 The AI of 1,500 mg for adults 19 through 50 years of age was derived based on the fol-
lowing rationale: a diet that provides an average of 1,500 mg/day of sodium can meet recom-
mended intakes of other nutrients; this level exceeds the levels of sodium intake that have been
associated with adverse effects on blood lipid concentrations and insulin resistance, and this
level allows for excess sodium loss in sweat by unacclimitized persons who are exposed to
high temperatures or who are moderately physically active (IOM, 2005). The AIs for children
and adolescents 1–18 years of age (1,000 mg/day for 1–3 years of age; 1,200 mg/day for 4–8
years of age; and 1,500 mg/day for 9–18 years of age) were extrapolated down from the AI
for adults using the average of median energy intake levels of the age groups for adults and for
children as the basis for extrapolation. The AI for adults 51 years and older (1,300 mg/day for
51–70 years of age and 1,200 mg/day for > 70 years of age) was extrapolated from younger
individuals based on energy intake (IOM, 2005).
3 Tolerable Upper Intake Level: IOM reference value: the highest average daily nutrient
intake level that is likely to pose no risk of adverse health effects to almost all individuals in
the general population. As intake increases above the UL, the potential risk of adverse effects
may increase.
4 Analytical support provided by Mathematica Policy Research, Washington, DC.
5 Available online: http://www.cdc.gov/nchs/nhanes.htm (accessed November 17, 2009).

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SODIUM INTAKE ESTIMATES FOR 00–00
to analyze data for this study are described in Appendix E. Information
from the analyses is summarized below, and more detailed data tables can
be found in Appendix F.
ESTIMATING SODIUM INTAKE
Although data based on the “disappearance” of sodium in the food
supply, as described in Chapter 2, can provide some information, two gen-
eral methods of assessing the population’s intake of sodium are considered
to provide reasonably accurate estimates: (1) dietary self-reports (inter-
views, food records, diaries, food frequency questionnaires of individuals)
and (2) urinary sodium measures of individuals.
The more accurate and reliable method of estimating sodium intake is
the analysis of urine collected during a 24-hour period, which reflects about
90 percent or more of the ingested sodium (Clark and Mossholder, 1986;
Luft et al., 1982; McCullough et al., 1991; Schachter et al., 1980). How-
ever, such measures are not currently included in national surveys carried
out in the United States. Therefore, available information on the U.S. pop-
ulation’s sodium intake is based currently on national survey data derived
from self-reported dietary intake of respondents. These large-scale national
surveys provide representative estimates for the total population and large
race/ethnic subgroups. However, NHANES data sets from 2003–2004 and
2005–2006 were combined for this study to provide larger sample sizes for
subgroup analysis (see Appendix F). Clinical trials and smaller-scale studies
can also provide dietary information for subgroups or special populations
that cannot be gleaned from national surveys, but these cannot be relied
upon to be representative.
For population-level or group intake estimates, multiple 24-hour di-
etary recalls are the preferred method (IOM, 2000). Other methods are
feasible, but require greater respondent effort and may alter behavior (e.g.,
food records and diaries) or overestimate food and energy intake (e.g., food
frequency questionnaires) (Thompson and Subar, 2008). The strengths of
the 24-hour dietary recall include the use of a standardized protocol to
quantify the types and amounts of foods consumed over the course of a
day, reduced respondent burden, and the provision of valid dietary intake
estimates for groups and usual nutrient intake if two or more 24-hour
recalls are collected for at least a subsample of the group. Also, individual
intake data permit calculation of intake distributions for groups so that
the prevalence of high and low intake can be estimated. Additionally, they
reflect the sodium content of foods as consumed.
The major limitation of any dietary intake method is that there is some
degree of misreporting and measurement error (Thompson and Subar,
2008). For example, overweight persons may underreport intake, omitting
certain foods or reducing the reported amounts; furthermore, parents may

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STRATEGIES TO REDUCE SODIUM INTAKE
overreport their young children’s intake and be unable to estimate amounts
accurately (Basch et al., 1990; Briefel et al., 1997; Devaney et al., 2004).
Twenty-four hour recalls are also labor intensive to collect, and at least two
non-consecutive days of data are needed to estimate usual intake.
Over the years, improvements in methodologies have been made as
part of the National Nutrition Monitoring and Related Research Program
(Woteki, 2003), and the quality and validity of data from 24-hour recalls
have been improved. Efforts have focused on training dietary interviewers
to use standardized probes to elicit complete and accurate reports of intake,
using appropriate measurement aids to help respondents report amounts,
and developing statistical adjustments to allow better estimation of usual
intake (Dwyer et al., 2003). Nonetheless, the intake estimates for sodium
derived from NHANES are likely to underestimate the population’s true
total intake. However, despite the inherent measurement errors in dietary
data collection and the underestimation of true total intake of sodium by
the population, these measures provide useful and relevant information.
CURRENT SODIUM INTAKE OF THE U.S. POPULATION
For the purposes of this study, intake data from the NHANES covering
2003–2006 (i.e., combination of the 2003–2004 and 2005–2006 surveys)
were used and designated as “current.” For analyses related to quantitative
sodium intake, estimates are provided as usual intake (see Appendix E);
analyses related to food categories as well as non-food contributions to
the diet are reported as 1-day means, as is sodium intake from earlier
NHANES.
As shown in Table 5-1, sources of dietary sodium include foods, salt
added at the table, tap water, and dietary supplements. The sodium content
of foods reflects salt added in cooking and food preparation. Methodologies
for estimating table salt, tap water, and dietary supplements are described
in Appendix E. Information on the contribution from medications was not
available for the committee’s analysis. Drugs including anti-inflammatories,
antacids, and laxatives can contribute to sodium intake.6 For example,
sodium bicarbonate is often used to alleviate heartburn and acid indi-
gestion.7,8 Although individuals with certain health conditions and their
physicians may need to be concerned about the sodium content of some
6 Available online: http://www.megaheart.com/pdf/sodiuminmedications.pdf (accessed June
3, 2009).
7 Available online: http://www.medicinenet.com/sodium_bicarbonate-oral/article.htm (ac -
cessed November 11, 2009).
8 For example, commercial antacid tablets have 10 mg of sodium per two tablets (ingredi-
ent is sodium polyphosphate), according to the 2008 Nutrition Dietary System for Research
database.

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STRATEGIES TO REDUCE SODIUM INTAKE
Tap Water 0.7
Table Saltb 4.9
Supplements
< 0.1
Fooda 94.3
FIGURE 5-1 Percentage contribution of dietary sources to total intake of sodium
for persons 2 or more years of age.
NOTES: Mean intake, 1 day, weighted 24-hour dietary recall data (n = 16,822);
sodium intake from food is reported as 5-1.eps
Figure a 1-day mean rather than usual intake to
be consistent with the data available for other dietary sources.
a Includes salt added in cooking and food preparation.
b Salt added by the consumer at the table.
SOURCE: NHANES 2003–2006.
through childhood and early adulthood, peaks at age 19–30 years, and then
declines (Appendix F, Table F-1). On average, other dietary sources beyond
foods provide an additional 207 mg/d of sodium, resulting in a mean total
sodium intake of 3,614 mg for the population ages 2 years and older. More
detailed information on mean intake and percentile distribution for usual
intake is presented in Appendix F, Tables F-1 and F-2, respectively.
Additional analyses reveal that the proportion of the population meet-
ing the 2005 Dietary Guidelines for Americans recommendation of < 2,300
mg/d for sodium is only 10 percent (standard error [SE] = 0.5 percent);
when only food sources are considered, 15 percent (SE = 0.6 percent) of the
U.S. population ages 2 years and older meets the recommendation. Older
women (71 years and older) are the most likely to meet the recommenda-
tion, but still only 36 percent (SE = 3 percent) consume < 2,300 mg/d.
Foods contribute the vast majority of dietary sodium, estimated at
3,407 mg/d for persons 2 or more years of age for 2003–2006 (Appendix F,
Table F-1). As shown in Figure 5-1, sources other than food contribute
less than 6 percent of dietary sodium. For this reason, intake from food is
discussed first.

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SODIUM INTAKE ESTIMATES FOR 00–00
Intake from Foods
By Age
Usual mean daily sodium intake estimates from foods are about 2,200
mg at ages 2–3 years, peak at about 3,800 mg at ages 19–30 years, and
decline slowly to about 2,600 mg above age 70 (see Figure 5-2 and Ap-
pendix F, Table F-5). Significant numbers within all age groups exceed the
UL. Appendix F, Table F-3 contains more detailed information on usual
intake percentile distributions for Dietary Reference Intake (DRI) age and
gender subgroups.
Median intake was compared to usual mean intake and found to be
slightly lower, an average of 50–150 mg lower per day, but median intake
tracks closely with mean intake (see Table 5-2 and Figure 5-2). More details
on median values can be found in Appendix F, Table F-3.
Usual mean sodium intake from foods exceeds the AI for all age groups,
shown for children and adults in Figures 5-3 and 5-4, respectively. This
indicates that there are no concerns about inadequate sodium intake in the
U.S. population.
Indeed, about 88 percent of Americans ages 2 years and older have
excessive sodium intake from foods, that is, intake above the UL. As shown
in Figure 5-5, sodium intake for a vast majority of people in all age groups
exceeds the UL. Persons over 70 years are the largest percentage with intake
below the UL; about one-third have usual sodium intake below the UL.
3,816 3,734
4,000 3,693
mean
Sodium Intake (mg/d)
3,280 3,234
3,699
3,500 3,582
3,531
2,796 3,212
3,000 3,122 2,651
median
2,736
2,500 2,201
2,574
2,000 2,144
1,500
2–3 4–8 9–13 14–18 19–30 31–50 51–70 > 70
Age in Years
FIGURE 5-2 Usual daily mean and median sodium intake from foods for persons
2 or more years of age.
NOTE: d = day; mg = milligram.
Figure 5–2 revised
SOURCE: NHANES 2003–2006.

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SODIUM INTAKE ESTIMATES FOR 00–00
TABLE 5-9 Sodium Density for Foods from Home and Away for Persons
2 or More Years of Age
Source of Food Sodium Density (mg/1,000 kcal)
Home 1,422
Away (total) 1,825
Restaurants 1,925
Fast food/pizza restaurants 1,805
School 1,629
Other 1,466
NOTE: “Home” includes foods purchased at the store and prepared at home; “restaurants”
includes those with waiters/waitresses and bar/tavern/lounge restaurants; and “other” includes
foods from child or adult care centers, soup kitchens, Meals on Wheels, community food pro-
grams, vending machines, food gifts, mail order purchases, street vendors, etc. kcal = calorie;
mg = milligram.
SOURCE: NHANES 2003–2006.
Other Approaches to Characterizing the
Sodium Content of the Food Supply
Other approaches can be used to describe the sodium content of the food
supply beyond examining the main contributors of sodium to the diet on the
bases of food category and types of eating establishments. However, as a gen-
eral matter, the food supply as a whole has not been systematically tracked
or monitored through surveys designed for this purpose. Alternatively, the
sodium content of the food supply can be described using salt disappearance
data (which can also be used to derive gross estimates of sodium intake). So-
called “market basket” studies, such as the survey conducted by the Food
and Drug Administration (FDA), could also be useful, although currently
it is designed primarily for other purposes. The national databases related
to food composition—which include sodium content and are maintained
by USDA—cannot themselves characterize the sodium content of the food
supply, but are instead a key component of the process of estimating sodium
intake based on dietary recalls from a nationally representative sample of the
U.S. population. However, selective comparisons of changes in food composi-
tion over time within these databases could provide some useful trend data
on changes in sodium in the food supply. The only available study of this type
did not include information on sodium (Ahuja et al., 2006).
Salt Disappearance Data
Monitoring intake from disappearance data allows for a reasonably
accurate estimate of time trend patterns because common methods of col-
lecting and accounting for use have remained similar over time. Salt disap-

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STRATEGIES TO REDUCE SODIUM INTAKE
pearance data can be used to estimate time trend patterns in the availability
of sodium for human consumption, with the understanding that there are
losses and wastage that cannot be accounted for. As described in Chapter 2,
the annual per capita salt disappearance data show a steady increase in per
capita availability between 1983 and 1998. While this does not definitively
indicate that there has been an increase in the overall sodium content of
the food supply, it is suggestive. More recently, values appear to be leveling
off or decreasing slightly. The peak levels in 1998 indicate that approxi-
mately 5,700 mg of sodium were available per person per day. Although
the pattern of use over time suggests that early educational and program
initiatives (such as in the early 1980s) were associated with a reduction in
salt use, subsequent programs, including the implementation of a manda-
tory declaration of sodium content on all food labels in 1993 and multiple
calls for food processors and food service operators to reduce the sodium
content of foods since 1969, appear to have had little or no impact on salt
availability for human use.
Market Basket Study: FDA’s Total Diet Study
The Total Diet Study (TDS) is an ongoing FDA program that deter-
mines levels of various contaminants and nutrients in foods.15 From this
information, dietary intake of those substances by the U.S. population can
be estimated. Since its inception in 1961 as a program to monitor radioac-
tive contamination of foods, the TDS has expanded to include pesticide
residues, industrial chemicals, and toxic and nutrient elements.
The TDS involves purchasing samples of food throughout the United
States, preparing the foods as they would be consumed (table-ready), and
analyzing the foods to measure the levels of select contaminants and nu-
trients. Dietary intake of these substances by the U.S. population is then
calculated by multiplying the levels found in TDS foods by the average
consumption amounts for each food. The outcomes for sodium are reported
as milligrams per kilogram of food. The number of different foods sampled
in the TDS has increased from 82 food items when the study was initiated
in the early 1960s to about 280 foods in the current program.
Sample collections (also referred to as market baskets) are generally
conducted four times each year, once in each of four geographic regions of
the country (West, North Central, South, and Northeast). Food samples are
purchased by FDA personnel from supermarkets, grocery stores, and fast
food restaurants in three cities in each region and are shipped to a central
FDA laboratory.
15 Available online: http://www.fda.gov/Food/FoodSafety/FoodContaminantsAdulteration/
TotalDietStudy/default.htm (accessed November 18, 2009).

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SODIUM INTAKE ESTIMATES FOR 00–00
The TDS analyzes sodium on composites, reports these as milligrams
per kilogram of food, and does not convert the results for composites back
to representative diets, thereby limiting the utility of the data on sodium
relative to the food supply. Further, it is unclear whether the sampling
scheme, food preparation, and documentation of product samples are suf-
ficient or appropriate for sodium. For example, issues related to the propor-
tioning of the sampling of vegetables among fresh, frozen, and canned may
require a different approach for sodium (which should be based on how
consumers consume them), given that the current focus is on contaminants
and pesticides.
National Food Composition Databases
In theory, national food composition databases offer the opportunity to
monitor changes in the sodium content of the food supply, but interpreta-
tion of such data is problematic. There can be a confounding effect due to
improvements in the food composition data and changes in the approaches
used to determine the listings for the sodium values of foods. Currently,
about 70 percent of the sodium values in the food composition database
used to code and assess sodium in NHANES 2003–2006 are analytical
values, 5 percent are from food labels, 11 percent from manufacturers, and
15 percent imputed. Moreover, during the time dietary trends have been
measured, the food composition database has been updated and expanded
to include more brand names and fast food items as well as a few other res-
taurant foods.16 Maintaining an up-to-date database on the sodium content
of foods is a challenging but essential task.
Ahuja et al. (2006) examined the effect of improved food composition
data on intake estimates in the United States through a reanalysis of data
using multiyear versions of the tables of food composition. Sodium was
not included in their analysis, but for the more than 25 nutrients and food
components examined, results showed minor but statistically significant
differences in mean intake estimates for most nutrients.
MONITORING
Monitoring intake of sodium and describing the nature of sodium
sources in the food supply is fundamental to implementing and sustaining
strategies to reduce sodium intake. While estimates of sodium intake based
on dietary recall methodologies are useful and readily reveal the high intake
levels among the U.S. population, more accurate methods for estimating
intake are available, including the 24-hour urine sample.
16 Personal communication, J. Holden, USDA, Washington, DC, September 11, 2009.

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STRATEGIES TO REDUCE SODIUM INTAKE
The collection of 24-hour urine specimens to assess sodium intake re-
flects the gold standard for estimating sodium intake, however this method
has not been included in the NHANES because of the complexity and cost
of such collections. NHANES has collected “casual” urine specimens to
assess environmental analytes, determine the possibility of pregnancy, and
measure kidney function and iodine status.17 However, these have not been
analyzed for sodium, and it is recognized that casual specimens are not
likely to provide a desirable level of accuracy for the purposes of estimating
intake. Nonetheless, because surplus collections of these samples have been
stored since NHANES became a continuous survey in 1999, these samples
offer the opportunity to carry out pilot studies relative to comparisons,
given that NHANES plans to collect a second urine specimen as part of the
recently initiated 2009–2010 survey.
All of the usual improvements frequently called for relative to estimat-
ing intake through dietary recall methods also apply to sodium. These
include advances in recall methods and probing techniques, enhancement
of food composition tables for sodium content of foods, and timely, user-
friendly releases of data. More frequent analysis and reporting of distribu-
tions of usual sodium intake (and energy for calculations of sodium density)
and food sources of sodium are warranted to better monitor sodium intake
and initiatives to reduce sodium. Of particular importance in the case of
sodium for food composition tables is the ability to incorporate into such
tables the sodium content of menu items offered by the major chain restau-
rant/foodservice operations.
Finally, there is considerable utility to be gained through the imple-
mentation of appropriate market basket studies and innovative approaches
to characterizing the sodium content of the food supply. The committee
considered these in more depth as described in Chapter 8.
REFERENCES
Ahuja, J. K. C., J. D. Goldman, and B. P. Perloff. 2006. The effect of improved food composi-
tion data on intake estimates in the United States of America. Journal of Food Composi-
tion and Analysis 19(Supplement):S7-S13.
Azoulay, A., P. Garzon, and M. J. Eisenberg. 2001. Comparison of the mineral content of tap
water and bottled waters. Journal of General Internal Medicine 16(3):168-175.
Basch, C. E., S. Shea, R. Arliss, I. R. Contento, J. Rips, B. Gutin, M. Irigoyen, and P. Zybert.
1990. Validation of mothers’ reports of dietary intake by four to seven year-old children.
American Journal of Public Health 80(11):1314-1317.
Bradshaw, M. H., and G. M. Powell. 2002. Sodium in drinking water. Manhattan, KS: Kansas
State University Agricultural Experiment Station and Cooperative Extension Service.
17 Available
online: http://www.cdc.gov/nchs/nhanes/nhanes_questionnaires.htm (accessed
November 18, 2009).

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